The present invention relates in general to an apparatus that utilizes a lamination process to transfer an overcoat from donor support to printed media. More particularly, this invention relates to an overcoat application peel apparatus for use in the lamination process done such that the donor support can be separated or peeled from the printed media leaving an overcoat behind on the printed media.
Durability of photographic and near photographic images has become a feature that has grown in demand in recent years. Current commercial means of improving durability include lamination with a clear adhesive liquid laminate material or coating (via spray or liquid application) with a liquid that dries to a clear protective layer. Another lamination process known as xe2x80x9cpeel apartxe2x80x9d lamination has been demonstrated for diffusion transfer images.
The focus of this particular invention is the peel apparatus used in the peel-apart thermal transfer lamination process. This technique transfers an overcoat material from a donor support to a printed image. This transfer is often done through a process in which the donor support with the overcoat and the printed media are brought together mechanically with pressure and then heat is applied for a specific exposure time period. This process causes the overcoat material to transfer from the donor to the printed image, so that the donor can then be peeled away.
One example of this technique uses a heated fuser and a platen to sandwich or press the donor support with overcoat and the printed media together in a mechanical nip. The donor support with overcoat and the printed media are then transported at a constant rate of speed between the heated fuser and the platen such that the exposure time and temperature are controlled. While in the nip, the thermal energy from the heated fuser causes the transfer to take place. The composite laminate carrying donor support, overcoat, and printed media are then transported and manipulated to separate the donor support from the printed media and its new overcoat layer.
The donor support and the overcoated printed media can not be easily separated directly upon exiting the nip of the heated fuser and platen. This is usually due to the fact that the overcoat material is in a phase state that does not allow it to have an adhesion affinity for the printed media that is greater than its affinity for the donor support. Therefore, a curing time must be allowed and a separation or peeling process must occur downstream of the nip. This separation or peeling mechanism is usually designed to maximize the following functional requirements:
a) The overcoat remains uniformly applied to the printed media.
b) No contamination is generated in the form of bits of unused or non-adhered overcoat.
c) No donor support or media transport jams are generated.
d) The process works over a wide range of printed media sizes and types, donor support and overcoat material types, and equipment settings.
Mechanisms designed to meet these requirements can be found in a multitude of patents and in practice. For example, in U.S. Pat. No. 5,658,416, MacCollum et al. describes a method and apparatus that uses a number of means for performing a peel of a laminate from another donor. The basic mechanism is one in which the separation of laminate carrying donor is done using a vacuum in conjunction with a peel angle. In addition, a beater blade is used near the separation point to aid the separation by introducing pulsating forces to the laminate carrying donors. In U.S Pat. No. 5,643,392, Clough describes a method in which tension control and a peel angle are used to separate laminate carrying donors. Schulte, Goodwin et al., and Mistyrik in U.S Pat. Nos. 5,820,277, 5,788,384, and 6,053,648 discuss other tension control means, respectively. Mistryrik describes a bowed plate for improved transport performance of the laminate carrying donors. Miyashita in U.S. Pat. No. 4,420,152 in which pawls are used to separate then laminate carrying donors describes another means. Finally, Pickering et al. describes in U.S. Pat. No. 5,499,880 a donor guide that has a similar function to the peel bar already described.
An example of the process in practice can be found in the Kodak Picture Maker. The Kodak Picture Maker is a commercial printer that uses a thermal dye diffusion to transfer both dye and a protective overcoat to printed media. Specifically, this printing process is one in which dye is transferred from a donor ribbon to media by means of heating a thermal printhead (instead of a fuser) while the printhead, donor ribbon and media are in mechanical contact. By performing this process in a serial fashion for three separate primary color patches (sometimes there is a fourth black patch) in a controlled manner, an image can be produced on the media. To ensure durability, this printing process is performed one more time except that instead of dye transfer, a continuous clear overcoat material is transferred to the media. The mechanism used to separate the donor support from the overcoated printed media is a peel bar. It is located downstream of the nip and is simply a mechanical feature the is used to define the geometric line along which the donor support is directed to a donor take-up reel and the overcoated printed media is directed toward the exit of the printer. The distance between the nip and the peel bar is critical in that it provides the curing time required performing a clean peeling action.
In the above cases, the base means for performing the peeling relies-on controlling the distance between the fuser and the peel bar or requires a peeling mechanism to aid the peel bar. These mechanisms can be expensive, and difficult to put and keep in position. In addition the prior art devices are not efficient causing lost hours and additional costs due to downtime. Finally many of these devices cause machine failures leading to expensive machine downtime and repairs.
Therefore there is a need for an improved peeler device that is low cost and effective for a wide range of printing processes and peel-apart materials. The intention of the invention is to describe a mechanism that meets these needs.
An object of the present invention is to provide an overcoat application process in which an overcoat material is transferred from a donor support to a printed image.
Another object of the invention is to provide a means by which the donor support and the printed image with an overcoat are separated or peeled apart in a controlled fashion such that the overcoat material remains uniformly applied to the printed image.
Yet another object of the invention is to provide a means by which the donor support and the printed image with an overcoat are separated or peeled apart in a controlled fashion such that no contamination is generated by the peeling action.
A further object of the invention is to provide a means by which the donor support and the printed image with an overcoat are separated or peeled apart in a controlled fashion such that the donor support and the printed image with an overcoat do not cause a transport jam.
A still further object of the invention is to provide a means in which the donor support and the printed image with an overcoat are separated or peeled apart in a controlled fashion such that the overall process has the ability to handle a wide variety of donor support, overcoat, and image material types and sizes within a specific equipment design.
In accordance with a further aspect of the present invention, there is provided an apparatus for performing the peeling process to separate the donor support from the overcoated printed media for use in the lamination process.
The apparatus including a first peel guide, a second peel guide adjacent the first peel guide and can also include a donor guide and a tilted platen.
The novel aspects of the invention are set forth with particularity in the appended claims. The above and other objects, advantages and novel features of the present invention will become more apparent from the accompanying detailed description thereof when considered in conjunction with the following drawings.